1. Field of the Invention
The present invention relates to an alignment adjusting mechanism for adjusting alignment of a probe and a measuring instrument.
2. Description of Related Art
There has conventionally been known a measuring instrument for measuring a profile of an object to be measured, including a probe provided with a stylus at a shaft tip, the probe and the object being relatively moved to bring the stylus into contact with a measurement portion of the object, whereby the profile of the object is measured from coordinates when the stylus is in contact with the object (see, for instance, Patent Document 1: JP-A-11-142141).
The instrument disclosed in Patent Document 1 includes a non-contact roughness probe for measuring surface roughness of the object and a touch signal probe having a stylus. When the stylus is displaced, a touch signal is output by a touch signal generator.
However, when a circumferential surface profile, cylindricity, depth and the like of a hole such as a screw hole and a deep hole are measured by using the above-described probe, inclination of a shaft 8B of a probe 8 relative to a center of a hole 901 as shown in FIG. 16 causes the shaft 8B to contact with a circumferential wall of the hole 901, thereby damaging the object or the probe 8. In order to solve such a problem, an arrangement in which a posture of a stylus is adjusted (alignment adjustment) has been proposed.
FIG. 17 illustrates a conventional alignment adjusting mechanism of a probe. FIG. 18 illustrates another conventional alignment adjusting mechanism of a probe.
As shown in FIG. 17, the conventional alignment adjusting mechanism is provided with a pin 903 formed at one end of a probe holder 902 for holding the probe 8 and is rotatably held by a bearing 906 of a base 905 that is fixed to a measuring instrument body 904. At the other end of the probe holder 902, a tension spring 907 is provided for biasing the probe holder 902 toward the base 905 and a push-in screw 908 is inserted into the probe holder 902. In accordance with a push-in dimension of the push-in screw 908, the probe holder 902 is rotated around the pin 903 to adjust the alignment of the probe 8.
FIG. 18 exemplarily shows another arrangement in which the probe 8 is fixed to a goniostage 909 fixed to the measuring instrument body 904. Specifically, the goniostage 909 includes a first stage 910 having a first circular sliding surface 910A and a second stage 911 having a second circular sliding surface 911A slidably connected to the first sliding surface 910A of the first stage 910. The probe 8 is fixed to the second stage 911. By sliding the second sliding surface 911A of the second stage 911 against the first sliding surface 910A of the first stage 910, the alignment of the probe 8 is adjusted. However, the alignment adjustment of the probe 8 according to the above conventional arrangements shown in FIGS. 17 and 18 causes a large displacement of a position of a stylus 8C. Particularly, when a fine profile is measured, alignment adjustment needs to be performed while the position of the stylus 8C of the probe 8 is confirmed by a microscope. However, when the position of the stylus 8C is largely displaced as described above, the stylus is out of a visual field of the microscope and the position of the microscope needs to be re-adjusted, which may lead to complication of operation(s). Furthermore, in the arrangement including the goniostage as shown in FIG. 18, when the goniostage is attached to a measuring instrument for particularly measuring a profile of a small-sized object (e.g., several mm in size), it is difficult to control a rotation angle of the second stage 911 and to manufacture the sliding surfaces 910A and 911A of the first and the second stages 910 and 911 respectively.